1. Field of the Invention
The present invention is generally directed to the field of servicing and repairing ball valves. More specifically, the present invention includes systems and methods for servicing ball valves in a variety of locations including on railroad tank cars.
2. Description of the Related Art
While others have proposed solutions to the problem of repairing and servicing ball valves, the existing proposed solutions to this problem are inadequate. Ball valves are used in a wide variety of fluid systems. They are typically utilized on fluid filled tanks or pipes as valves for releasing fluid when desired. They are typically highly reliable and employ few moving parts. However, the life of a ball valve is not limitless. The seals employed by a ball valve will wear out over time.
A typical ball valve assembly is comprised of a first circular or ring seal member that is placed adjacent to one orifice in the valve. The ball member of the ball valve is located adjacent to this seal member. The ball member is comprised of a spherical member that has a through passage, typically cylindrical, that extends from one side to the other. The ball valve also typically includes a second ring seal located adjacent to the ball member so that the ball valve housing presses against it thereby providing a tight compression fit between the seals, the ball member and the orifice. The ball member may be mechanically rotated so that in a first position no fluid is allowed to flow because the ball member forms a seal with the first and second (or upstream and downstream) seal members. When the ball member is rotated, the through passage is then aligned with the orifice, thereby allowing fluid to flow.
Conventional methods for servicing and repairing ball valves typically require that the fluid container or pipe to which the ball valve is secured be completely drained so that fluid will not flow from the tank or pipe when the ball valve is being serviced. While in many instances this is not a problem, there are certain circumstances where it is difficult or otherwise undesirable to remove all of the fluid from a tank or pipe on which a ball valve is located. For example, in the railroad industry, when ball valves on railroad tank cars require service, the conventional solution is to completely remove all the fluid from the tank car so that the ball valve attached to the car may be serviced. This is difficult and often highly undesirable, particularly if the car that requires service is out in the field away from the service depot or cleaning facility.
One characteristic of ball valves is that the downstream seal typically fails prior to the upstream seal member of the ball valve. This is due to the fact that when a ball valve is used for draining fluid from a tank, the ball valve is usually located in a lowermost region of the tank. This is for the obvious reason that fluid needs to flow from the tank when it is being drained. For example, most railroad tank cars typically include a ball valve located in the lowermost point of the tank car. Due to this location, the fluid in the tank typically applies a significant downward force on top of the ball member thereby applying greater pressure to the downstream or second seal member of the ball valve. This increases the wear on the downstream seal member of the ball valve. As a result, ball valves require servicing at various intervals. However, another characteristic of ball valves, due to the design characteristics recognized above, is that the downstream seal member will need to be serviced more often than the upstream or first seal member.
Currently there is no known system for easily and conveniently servicing ball valves on railroad tank cars or, in other locations which can be safely used on cars, tanks and pipes that have not otherwise been pulled from normal operation to be cleaned. U.S. Pat. No. 5,975,104 discloses a ball valve seal replacement apparatus and method. However, the systems and methods described in that patent require the use of a jig and a jack-screw which is cumbersome and may be difficult to use. Accordingly, there remains a need in the field for improved systems and methods for servicing ball valves.
The present inventor has overcome the shortcomings of the prior art and identified new systems and methods for repairing and servicing ball valves on railroad tank cars as well as other locations. Other objects and advantages of the present invention will be apparent from the following summary and detailed description.
The present invention is directed to improved systems and methods for servicing and repairing ball valves on railroad tank cars as well as ball valves in other locations and structures. In accordance with the present invention, a temporary ball valve support structure is utilized to apply pressure on the downstream portion of the ball member in the ball valve so that a seal is maintained between the ball member and the upstream seal member which is the seal member closest to the tank, pipe or other adjacent structure. This prevents fluid from leaking from the valve while the valve is being serviced by ensuring that there is a good seal between the ball member and the seal closest to the fluid filled tank.
In accordance with the present invention, a temporary ball valve support is provided which allows the downstream ball valve seal and the downstream ball valve housing assembly portion to be removed. This allows the downstream seal to be replaced and/or serviced without requiring fluid to be removed from the tank. In one embodiment, the temporary support may be secured to the downstream portion of a fluid tank, or to the downstream portion of the valve. Alternatively, the temporary support may simply be supported by the ground beneath a railroad tank car, pipe or other fluid tank, or secured to another structure.
All that is necessary is that the temporary support provide a secure foundation for applying a force against the ball member of the ball valve. In the preferred embodiment of the present invention, the system and method employs first and second ball support members in the form of levers. These two members are utilized in order to ensure that force may be applied to the ball member at all times when the ball valve is being serviced.
In utilizing the systems and methods of the present invention, the temporary ball valve support is initially secured beneath the ball valve. The temporary support structure may be secured directly to an adjacent tank or pipe connected to the ball valve or any other adjacent structure including the floor or ground beneath the ball valve.
After the temporary support structure has been secured, a first ball support member is inserted within the temporary ball valve support. This first ball support member applies a force on a portion of the ball member thereby ensuring that the seal is maintained between the ball member of the ball valve and the upstream or first seal member. Once this occurs, and while force is being applied from the first ball support member, the downstream or second seal member and any other necessary portions of the ball valve assembly may be detached from the valve.
The portion of the downstream ball valve assembly and the downstream seal member are dropped down around the first ball support member. The first ball support member maintains a force on the ball member to maintain a seal between the ball member and the upstream seal. Once the downstream ball valve assembly portion and the downstream or second seal member have been lowered around first ball support member, a second ball support member is secured within the temporary support structure.
The second ball support member then applies a force against the ball member of the ball valve thereby joining the first ball support member in forcing the ball member against the first seal. The first ball support member is then removed, thereby allowing the downstream seal and ball valve assembly portions to be freely removed. The downstream seal member may be serviced and/or replaced. This is accomplished simply by securing a new downstream seal member around the first ball support member, if the seal is being replaced, along with any other necessary parts from the ball valve assembly.
The first ball support member is then utilized to apply a force against the ball member while a force is also applied by the second ball support member. The second ball support member may then be removed while a force is still applied by the first ball support member. This is necessary so that the lower seal assembly may be secured to the valve while preventing the ball valve from leaking. The first ball support member may then be removed after the downstream seal member and all of the ball valve assembly components are secured in place. Finally the temporary support structure also is removed.
Thus, servicing of the ball valve can be accomplished without requiring that fluid be removed from the tank. Those skilled in the art will appreciate that although the invention has been described with respect to a vertical ball valve arrangement, it will work equally well with any other ball valve arrangement, as all that is required is that the system and methods utilized in accordance with the present invention apply a force on the ball member of the ball valve to ensure that a seal is maintained between the ball member of the ball valve and the upstream or first seal member.